Snap switch



May 8 1951 w. voN sTOEsr-:R 2,551,714

SNAP SWITCH Filed May 9, 1950 'zanfme' (B Z//aZeT' Z/ongfoeser M7 aghi?,

Patented May 8, 1951 UNITED? STATES PATENT OFFICE SNAP SWITCH Walter Von Stoeser, Lake Villa,4v Ill., assgnor, liyI mesne assignments, to Moco; Products; Inc:, Chicagolll;, a corporationl of Illinois 3 Claims;

1i This invention relates to improvements in snap-action'switches-of the type commonly know-n as-stack or leaf -spring switches, such-as eXempli flexed a certain amount, thel over-center spring' arrangements being contrived in: anumber or different forms of construction` to aehieve'various-operating and manufacturing desiderata.

The prese t improvements pertain especially to detailsof the snap-action mechanism which prolong the operating life-oithey switch; affordAA very good Contact pressuresonbotlfi` sides ofthe throw, stabilize the operation ottheoverecenter spring, and permit: various spacings ofthestationary contacts without any attention to` the" spring tension or angularv attitude;

Other objects andaspectsY of utility-'inthe improved switch*structure-pertain*to details of: the construction and operation of: the'embodiment described hereinafter in view of thev annexed drawing,v inwhich:

Fig; lis aside elevation of' the'-switch; Fig; 2 is a top plan viewoffthe same.;Y

Fig. Sis an enlarged, fragmentary'section' taken'V along linesV -iifof Fig. 2 :l

Fig. fi is a perspective assembly detail'of the improved overcenter spring means In Fig. lis shown a simple stack .switch consisting of a pair of" opposite', rigid; stationary lcontacts Iii and lI, secured in spaced relation between insulating wafers in the stack l2, whichx is held tightly assembly by bolts IBI Also mounted in the stack is a flexible or movable contactor it (Fig. 3, also) which is intended to be moved back andforth-between the two` stationary contacts I andV I If.

Snap-action of the movable contact is eieeted:

through theagency of an operator arm I5, which is of spring metal, also, but which is longer than all ofv the other contact elements, but like the`v others; ha'slone of its-ends4 fixed in'- the stack; l2: Betweenits end regions', the operator armi i5 has a longitudinally extensive cut-out area It,

which vis large .enough to `permit the vmovable'oontactor l 4 to passl up-a-nddown -in directionsoppo# site to the back andiforth motions of the *operator-arm I5.v

T-he snap-action means is shown to advantage in- Fig. 31 and! includes a peculiarly shaped bow springl I8\ (see Fig. 4)A havingy a transverse armv I9? atA oneside oithe bow, and an odset 2ty at the-other side of the bow.

The bow spring I8' is` attached to the'operator arm adjacent the tongueI IliA and' free end of blade I4! by means; of la rivet 2|, andV preferably the offset 2D is provided with a small positioning lug 22, which ts into a punched' opening 23` in the operator arm.

The lateral arrn- I 9r ofthe especially 'shaped snap spring aordsftworngers 19A and ISB, which are causedj torest- (Fig. 2)- on theopposite sides of the'operat'or arm borderingthe cut-out; thetension ofthe bow spring and the-xation ofthev rivet means 2-I being intended to bias the spring so that said fingers ISA and1 H1B locate the spring in apredetermined attitude and condition of" slight tension.

The aforesaid biased-locating of the bow-springh'asas one of' itspurposes the registration of an actuator slot 243 (Figs 3 and 4) in the bow spring in a desired position approximatelywithin the' .plane ofthe operator arm, or inother terms, practically inside-the cut-out area. of said arm, the impor-tance of which will becomemore apparent hereinafter.

The snap-action mechanism is completed by the-provision of ay throw member or actuator 2t, having 'anendwisetongue- 25 fitting into the spring slot" 24, and also having an endwise offset 21T infw-hich is a sl'ot 213 receiving the endwise tongue IIIA` off the-'contactor blade. The actuatorslot 28- is below theregister-ed oraligned positioniof the-spring slot 2li-in the normal condition of the switch (i. e. asinFig. 1)`l Fig. 3 shows the switch in operated condition,

from which it'will belobservedthat the bow spring' I8 cannot-be displacedvdownwardly from its registeredf position asA determined by the aligning means-orfngersA I'9A, ISB,l notwithstanding that the thrust'- of the actuator 26- in this attitude' would tend to displace the bow spring down-4 tacts IIJ-44, and without any practical decrease of contact pressure.

In the absence of the positioning and limiting means I 9A, I SB, the resultant displacement of the spring I8 under the foregoing conditions of overtravel would be at once apparent in an opening of the switch at a time when it is supposed to be closed, or an objectionable relaxation of the contact pressure.

The contact pressure in the normal condition of the switch is mainly dependent upon the resilience and bias of the movable blade II. In the present construction, this bias can be quite strong, giving maximum normal contact pressure, without making the switch sluggish or unreliable in snap-action, owing to the maintainance of the spring bow always in the same normal position as determined by the positioning means IQA, IlB. There is a minute movement of the parts 29A, I 9B on the sides of the operating arm I 5, but no objectionable wear results from this.

The contact spacing or clearance for a given switch size can be altered through a range of many thousandths of an inch without the necessity of adjustment or change in the over-center snap-action, the device in these respects operating as satisfactorily at a contact clearance of ten- 1,000th inch as at sixty-two 1,000th inch in the proportionate size illustrated.

The spring bow and associated over-center parts have an exceptionally long operating life even under extreme conditions inclusive of continuous, very rapid operation.

In prior types of snap switch of this class the spring bow is appreciably displaced at some phase of the overcenter movement, and this changes the relative positions of the toggle, rocker, or othei` over-center actuator, and the spring, particularly at the point of engagement of these parts. But in the present improvement, it will be noted by comparison of Figs. 1 and 3, that the juncture points at 24-25 are not appreciably displaced from the plane of the operating blade I5 in the operated and normal positions of the moving blade I 4 and operating blade I5; and that it is the actuator or throw-element 25 which changes angularly with respect to the bow spring.

Since the spring I8 cannot move downwardly and the juncture 24-25 is at the fulcrum of the lactuator 26, the latter at its tongue'25 in slot 24 likewise moves almost imperceptably, so that the displacement of the actuator 2 is translated mainly into a useful compressive thrust against spring IS at the point of engagement 2li-25 therewith, and the over-center action is smooth and reliably uniform up to and beyond dead center, whereas in the types of over-center mechanism in which the spring can move in an arc, a considerable change in both the angle and mag nitude of thrust occurs rapidly in the region of dead center, and not only results in useless lost motion, but such devices often require critical adjustment or production tolerances, and are likely to be unreliable if not properly operated or if they are exposed to any rough treatment or abuse.

Another advantage of the improved spring means resides in the fact that the operating arm need not be formed, which is to say that it may be used just as it comes from the die without any crimping, bending, or other adjustment, as is the case with certain prior spring devices of this class.

In the absence of the disclosed locating means to prevent downward movement of the spring I8, and to maintain the bow under tensiomthisv out in which the free end of the moving blade can move, stop contacts flanking the moving blade to limit the throw thereof, a bow spring having one end offset and fastened at a margin of the cut-out in the operating blade remote from the free end of the moving blade, said bow spring having a lateral arm at its opposite end and bearing upon opposite margins of said cut-out to align the spring in the cut-out against displacement therefrom in one direction, at least,

d and an actuator member having tongue and slot engagement with said free end of the moving blade and with said bow spring at a point close to said lateral arm thereof and which is substantially in the plane of said operating blade.

2. In a snap-action switch, a movable contactor blade held at one end, means flanking the free end of the contactor blade to limit its movements, an operating blade similarly held at one end in parallel assembly with the contactor blade and having an opening through which said free end of the contactor blade may pass, a bow spring having an end regionattached to said operating blade I in said opening and having means at an opposite end region engaging opposite sides of said opening in the operating blade to dispose said spring in a certain position in said opening and prevent movement of the spring in a certain direction out of said opening, and a throw-actuator having relatively oiset means at its opposite ends respectively loosely engaging said free end of the contactor blade and said opposite end region of the bow spring to throw the contactor blade responsive to movements of the operating blade.

3. In a snap-action stack-switch of the class described and having an operating arm with a cut-out, and a moving contact blade with a free end portion working in said cut-out, improvements in a snap-action mechanism comprising; the following, to wit: a bow spring fastened on said operating arm in said cut-out adjacent the free end of said operating arm, and aligning means on said bow spring for engagement with marginal portions of said cut-out to dispose said spring in a predetermined condition of alignment, and a throw lever operatively connected with said free end of the moving contact blade and having a movable operating connection with said bow spring at a point on the latter which is substantially within the plane of said operating blade.

WALTER VON STOESER..

REFERENCES CITED The following references are of record in the le of this patent:

Von Stoeser Mar. 14, 1950 

